Tundra plant diversity as influenced by biotic interactions

Report from Virve Ravolainen, Department of Biology, University of Tromsø
Project 200501253-6

Financial support to the project
“Vegetation in reindeer summer pastures”

Centre for Sámi Studies has kindly supported my fieldwork the summer of 2005. My PhD project is part of a multidisciplinary project, “Ecosystem Finnmark”, which focuses on the causes and effects of the varying reindeer numbers in the summer pastures of the coastal Finnmark.
The general aim of my Ph D study is to investigate plant diversity – productivity relationships in low – alpine vegetation. I am particularly interested in the effects of varying reindeer numbers on diversity of plant functional groups (e.g. herbs, dwarf shrubs), which in turn are expected to cause changes in the productivity of the vegetation. The summer pastures of reindeer largely consist of low – alpine areas, and another main interest for me is to gain understanding of the interactions between the actors of the food web in these ecosystems.

Finnmark

This summer, a field study was initiated on Varanger – peninsula, in the easternmost part of Finnmark, in co – operation with the “Arctic fox” – project. We aim to investigate the strength of interactions in the tundra food web. My focus is on plants, the primary producers of the tundra. Willow thickets were chosen as the spatial strata of this study, mainly because they are important foraging habitats, and provide shelter for smaller animals. Willow thickets are productive areas in a landscape of barren heaths, and both the thickets and the surrounding meadows are responsive to grazing. Several studies have shown that reindeer grazing severely affects willow height, density, and recruitment.

Willow thickets in Komagdalen, Varangerhalvøya, photo Christian Uhlig

Two river valleys were selected for this study and permanent study areas were established around the willow thickets that line the riverbank with a varying degree of fragmentation. This first year, vegetation composition was analysed, a pilot experiment for plant productivity was conducted, and density and activity of animals was estimated, along with some environmental parameters. This study will continue the following years with further monitoring of the plant and animal parameters, and the results from the first year will be analysed during the winter 2006.

The financial support from the Centre for Sámi Studies greatly aided the fieldwork in terms of salaries for a field assistant in this phase of establishing study areas and conducting the vegetation analyses. Results from this first year study will largely be used as bases for planning further field research. I appreciate this support and want to thank the Centre for Sámi Studies for this.